초록 ▼

A closed-loop circulating system for drilling wells has control of the flow rates in and out of the wellbore. Kicks and fluid losses are quickly controlled by adjusting the backpressure. Kick tolerance and tripping margins are eliminated by real-time determination of pore and fracture pressure. The

A closed-loop circulating system for drilling wells has control of the flow rates in and out of the wellbore. Kicks and fluid losses are quickly controlled by adjusting the backpressure. Kick tolerance and tripping margins are eliminated by real-time determination of pore and fracture pressure. The system can incorporate a rotating BOP and can be used with underbalanced drilling.

대표청구항 ▼

The invention claimed is: 1. System for operating a well that is being drilled with a drill string to provide a wellbore having a drilling fluid circulated therethrough via inlet and outlet streams, wherein the well is kept closed at all times, wherein the system comprises: a) a pressure containmen

The invention claimed is: 1. System for operating a well that is being drilled with a drill string to provide a wellbore having a drilling fluid circulated therethrough via inlet and outlet streams, wherein the well is kept closed at all times, wherein the system comprises: a) a pressure containment device to the wellbore which keeps the wellbore closed at all times while it is being drilled; b) means for measuring at least one of mass flow, volumetric flow, mass flow rate and volumetric flow rate on the inlet and outlet streams and generating flow signals, wherein monitoring means are located on lines in and out and are operated continuously throughout a given operation; c) at least one pressure sensor to obtain pressure signals, wherein the at least one pressure monitoring sensor is located at the wellhead or at the bottomhole and is operated continuously throughout a given operation; d) a central data acquisition and control system provided with software for predicting a real time signal; e) means for injecting drilling fluid through an injection line through which said fluid is made to contact said flowmeans, and said pressure sensor, and recovering drilling fluid through a return line; f) means for collecting drill cuttings at the surface; g) means for collecting flow signals; h) means for collecting pressure signals; i) means for directing all the collected signals to the said central data acquisition and control system; the software of the central data acquisition and control system considering, at each time, a real time predicted signal; the system further comprising j) a pressure or flow control device on the outlet stream to control the flow out of the well and to keep a back pressure on the well; and k) means to send a command from the central data acquisition and control system to the pressure or flow control device designed to adjust the volumetric or mass flow rate in the return line or pressure inside the wellbore; and the central data acquisition and control unit being programmed to compare said real time predicted signal to the signal; wherein the system acts on the principle of volume or mass conservation to determine the difference in volume or mass being injected and returned from the well; said determining compensates for factors including increase in hole volume, additional mass of rock returning as an indication of the nature of the fluid event occurring downhole; said comparison yielding any said discrepancy, said software also receiving as input any early detection parameters, wherein the input triggers a chain of investigation of probable scenarios, to ascertain that an influx or loss event has occurred; and converting said discrepancy to a value for adjusting the pressure or flow control device and restoring the predicted signal, wherein the software on identifying the influx or loss event, automatically sends a command to the pressure or flow control device designed to adjust the return flow rate or pressure inside the wellbore so as to restore the said signal to the predicted signal, thereby preemptively adjusting backpressure to immediately control the event without interruption of the drilling operation and wherein the system is a closed loop system, whereby monitoring means continuously provide date to the central data acquisition and control system whereby a predicted signal is continuously revised in response to any adjustment of actual signal value, adjusting ECD wherein the system further comprises a means for controlling equivalent circulating density which is defined as hydrostatic pressure plus friction losses occurring while circulating fluid converted to equivalent mud density at the bottom of the well, and continuously or intermittently drilling a gas, oil or geothermal well wherein drilling is carried out using bottom hole pressure chosen from one of the group comprising of: being a value intermediate the pore pressure and the fracture pressure of the well and able to directly determine either or both values if desired; being the exact bottom hole pressure needed, with a direct determination of the pore pressure; or being bottom hole pressure regulated to be just less than the pore pressure (known as underbalanced drilling) thus generating a controlled influx which may be momentary in order to sample the well fluid in controlled manner or may be continuous in order to produce well fluid in controlled manner. 2. System as claimed in claim 1 comprising at least one pump and a dedicated fluid injection line for injecting fluid direct to an annulus for the purpose of pressuring the wellbore through the annulus, independently of the current fluid injection path, and monitoring flow, pressure and optionally temperature the annulus provided between the drill string and the wellbore or a zone thereof, together with dedicated flow meters and additional means such as pressure or flow control devices, pressure or temperature sensors and the like. 3. System as claimed in claim 1 wherein the at least one pressure sensor is located at the surface or at the bottom hole. 4. System as claimed in claim 1 comprising two or more pressure containment devices in series throughout the well bore whereby a pressure profile may be established throughout the well and two or more pressure or flow control devices in series or parallel. 5. System as claimed in claim 1 comprising more than two pressure or flow control devices in series whereby a pressure profile is established in independent pressure zones created throughout the length of the well, wherein restrictions or pressure or flow control devices define the interfaces of each zone. 6. System as claimed in claim 1 wherein the drilling fluid is selected from at least one of oil and water liquid phase fluids and a combination with gas phase fluids or lightweight fluid. 7. System as claimed in claim 1 comprising means for monitoring values for rate of penetration, rock and drilling fluid density, well diameter, in and out flow rates, cuttings return rate, bottomhole and surface pressures and temperatures, torque and drag and basing calculations taking into account these and others for predicting ideal signal value. 8. System as claimed in claim 1 wherein the said central data acquisition and control system is provided with a time-based software to allow for lag time between in and out flux. 9. System as claimed in claim 8 wherein said software is provided with detection filters or processing filters to eliminate or reduce false indications on the received signals, and any other measured or detected parameters. 10. System as claimed in claim 1 which comprise three safety barriers, the drilling fluid, a blow-out preventer equipment and the pressure containment device. 11. Method for constructing a system as claimed in claim 1 said method comprising the steps of: a) providing a pressure containment device to the wellbore; b) providing means for measuring and monitoring at least one of volumetric flow, mass flow, volumetric flow rate and mass flow rate an the inlet and outlet streams and obtaining flow or flow rate signals, wherein monitoring means are located on lines in and out and are operated continuously throughout a given operation; c) providing at least one pressure sensor to obtain and monitor pressure signals, wherein the at least one pressure monitoring sensor is located at the wellhead or at the bottomhole and is operated continuously throughout a given operation; d) providing a central data acquisition and control system provided with software for predicting a real time signal; e) providing means for injecting drilling fluid through an injection line through which said fluid is made to contact said flow means, and said pressure sensor, and recovering drilling fluid through a return line; f) providing means for collecting drill cuttings at the surface; g) providing means for collecting flow signals; h) providing means for collecting pressure signals; i) providing means for directing all the collected signals to said central data acquisition and control system; j) the software of the central data acquisition and control system considering, at each time, a predicted signal; the method further comprising k) providing a pressure or flow control device on the outlet stream to control the flow out of the well and to keep a back pressure on the well; l) providing means to send a command from the central data acquisition and control system to the pressure or flow control device designed to adjust the fluid or mass flow rate in the return line or pressure inside the wellbore; and the central data acquisition and control unit being programmed to compare a real time predicted signal to the corresponding actual signal; wherein the system acts on the principle of mass or volume conservation, to determine the difference in mass or volume being injected and returned from the well; said determining compensates for factors including increase in hole volume, additional mass of rock returning as an indication of the nature of the fluid event occurring downhole; said comparison yielding any said discrepancy, said software also receiving as input any early detection parameters, wherein the input triggers a chain of investigation of probable scenarios, to ascertain that an influx or event has occurred; and convening said discrepancy to a value far adjusting the pressure or flow control device and restoring the predicted signal value, wherein the software on identifying the influx or loss event, automatically sends a command to the pressure or flow control device designed to adjust the flow rate in the return line or pressure inside the wellbore so as to restore the said flow rate in the return line or pressure inside the wellbore to the predicted ideal signal value, thereby preemptively adjusting backpressure to control the event without interrupting the drilling operation and wherein the system is a closed loop system, whereby monitoring means continuously provide data to the central data acquisition and control system whereby a predicted signal is continuously revised in response to any adjustment of actual signal value, adjusting ECD. 12. Method for constructing a system as claimed in claim 11 comprising at least one temperature sensor to measure temperature, wherein the method comprises additionally in step h) providing means for collecting temperature signals, and in step i) providing means for directing temperature signals to the central data acquisition and control system wherein the method additionally compensates for compressibility changes as an indication of the fluid event occurring downhole. 13. Method as claimed in claim 11 wherein a predicted and actual signal is at least one of predicted and actual flow out of the well, and predicted and actual pressure in the well, and predicted and actual ECD. 14. Injection line of a system according to claim 1 comprising a pump and sensors for fluid flow, and means for sealingly engaging with the well for injection into an annulus for the purpose of pressuring the wellbore through the annulus, independently of the current fluid injection path, and monitoring flow, pressure and optionally temperature, the annulus provided between the drillstring and the wellbore. 15. System as claimed in claim 1 wherein a predicted and actual signal is at least one of predicted and actual flow out of the well, and predicted and actual pressure in the well, and predicted and actual ECD. 16. Return line of a system for operating a well that is being drilled with a drill string to provide a wellbore having a drilling fluid circulated therethrough via inlet and outlet streams, wherein the well is kept closed at all times, wherein the system comprises: a) a pressure containment device to the wellbore; b) means for measuring at least one of mass flow, volumetric flow, mass flow rate and volumetric flaw rate on the inlet and outlet streams and generating flow signals; c) at least one pressure sensor to obtain pressure signals; d) a central data acquisition and control system provided with software for predicting a real time signal; e) means for injecting drilling fluid through an injection line through which said fluid is made to contact said flowmeans, and said pressure sensor, and recovering drilling fluid through a return line; f) means for collecting drill cuttings at the surface; g) means for collecting flow signals; h) means for collecting pressure signals; i) means for directing all the collected signals of different drilling parameters to the said central data acquisition and control system; the software of the central data acquisition and control system considering, at each time, a real time predicted signal; the system further comprising j) a pressure or flow control device on the outlet stream to control the flow out of the well and to keep a back pressure on the well; and k) means to send a command from the central data acquisition and control system to the pressure or flow control device designed to adjust the volumetric or mass flow rate in the return line or pressure inside the wellbore; and the central data acquisition and control unit being programmed to compare said real time predicted signal to the signal; wherein the system acts on the principle of volume or mass conservation to determine the difference in volume or mass being injected and returned from the well; said determining compensates for factors including increase in hole volume, additional mass of rock returning as an indication of the nature of the fluid event occurring downhole; said comparison yielding any said discrepancy, said software also receiving as input any early detection parameters, wherein the input triggers a chain of investigation of probable scenarios, to ascertain that an influx or loss event has occurred; and converting said discrepancy to a value for adjusting the pressure or flow control device and restoring the predicted signal, wherein the software on identifying the influx or loss event, automatically sends a command to the pressure or flow control device designed to adjust the return flow rate or pressure inside the wellbore so as to restore the said signal to the predicted signal, thereby preemptively adjusting backpressure to immediately control the event and wherein the system is a closed loop system, whereby monitoring means continuously provide data to the central data acquisition and control system whereby a predicted signal is continuously revised in response to any adjustment of actual signal value, adjusting ECD the return line comprising one or more return line segments in parallel each comprising a pressure or flow control device and sensors for flow out. 17. A return line as claimed in claim 16 comprising a degasser which is suited for insertion in the return line to operate in a desired pressure range. 18. A return line as claimed in claim 16 for location at the ground surface or at the seabed.